Fordham Senior Tackles Tiny Particles and Tough Problems

In the field of particle physics, the Standard Model details the behavior of elementary particles. Within this discipline is a field known as quantum chromodynamics (QCD) that specifically describes the interactions of particles known as quarks and gluons which combine to form subatomic particles such as protons and neutrons. Understanding the behavior predicted by QCD requires complicated equations and calculations, so Dr. Christopher Aubin of the Physics Department utilizes lattice quantum chromodynamics to make projections from the theory. This method computationally simulates the behavior of particles on a four-dimensional grid, allowing physical predictions about the interactions to be made.

Armed with the advantages of lattice QCD, FCRH senior Nick Geiser seeks to elucidate the properties of an individual particle known as the muon, a charged elementary particle that is similar to the electron. Specifically, Geiser is studying a quantity known as the anomalous magnetic moment of the muon, essentially a measure of the particle’s magnetic strength. The theoretical calculations of this value using lattice QCD aim to complement experimental methods to confirm the Standard Model.

Geiser is attempting to calculate the anomalous magnetic moment of the muon by first calculating the hadronic contribution from a quantity known as the hadronic vacuum polarization function. This method is based on a recent paper by Dr. Aubin that examines the effects of finite volume from the lattice on the hadronic vacuum polarization and the subsequent effects on the anomalous magnetic moment of the muon. However, Geiser’s calculations will consider more complicated processes than those presented by Dr. Aubin, utilizing particle interactions whose diagrams include two closed loops rather than Dr. Aubin’s one. The study will ultimately include a mixture of calculations by hand and computer simulations.

Geiser expects that his calculations will improve on Dr. Aubin’s findings, yielding a more precise value for the anomalous magnetic moment of the muon. Though the calculations should not greatly differ from the established findings, Geiser’s project seeks to strengthen current observations of finite volume effects on the hadronic vacuum polarization and anomalous magnetic moment of the muon.